Immune changes during long-duration missions

Immune changes during space flights in cx- ccss of two weeks have been almost exclusively studied by Russian investigators. Most of these studies have corn- pared postflight values with those obtained before flight. In a very few cases, analyses have also been atternpted during flight or with samples collected during flight. Studies of cosmonauts during spaceflight have shown that IgG levels were unchanged, whereas IgA and 1gM levels were sometimes increased. Additionally, inflight delayed type hypersensitivity testing demonstrated a decrease be- low the warning level in 1/3 of the cosmonauts tested. Pre- vS. postflight analyses have often revealed a postflight decrease in: PHA-triggered lymphocyte blast transforma- tion; the proliferation index of T-lymphocytes in the xenogeneic graft versus host reaction; the mitogen- induced production of interleukin-2; the presence of cer- tam leukocyte sub sets; and cytotoxic activity of natural killer cells. Other factors that either did not change, or changed in an apparently random manner after flight in- cluded: production of a and 'y interferon; autoimmune tests; and globulin classes. J Leu.koc. Biol. 54: 189-201; 1993.